1. Technical Field
The present disclosure relates to medium temperature solid fuel cell glass packaging material, in particular, to glass packaging material using Si—Al—Y—Zn as a glass main body with at least one glass modifier added, for increasing the thermal expansion coefficient and improving the bonding characteristics of the glass packaging material which therefore could be applied in other high temperature packaging environment.
2. Description of Related Art
In the fuel cell technology field, solid oxide fuel cells (SOFC) are associated with higher energy transfer efficiency, could select from multiple fuel sources, and are of the relatively lowered manufacturing costs. That said, SOFC needs to operate at high operating temperatures such as the range between 600 and 800 degrees Celsius. In the plate-type SOFC, therefore, high temperature packaging becomes necessary for filling the gap between the plates by the packaging material, in order to isolate the fuel gas from the oxygen. In short, the packaging material is used for bonding the materials/components and ensuring the air-tight SOFC with respect to its surrounding environment.
In a paper written by Shouguo Huang et al. and published in Journal of Alloys and Compounds, Si—AL—Y—Ba—B glass has been proposed. Such glass is made of SiO2 (3.53 wt % and 6.97 mol %), Al2O3 (7.21 wt % and 8.39 mol %), Y2O3 (10 wt % and 5.27 mol %), BaO (60 wt % and 46.55 mol %), and B2O3 (19.26 wt % and 32.83 mol %). As previously mentioned, SOFC needs to be operating in the high-temperature environment (such as in the temperature range between 600 and 800 degrees Celsius), and therefore the usage of the alkaline earth elements and the connecting members between the components of the fuel cell together could generate compounds such as MgCrO4, Ba3CaSi2O8, BaCrO4, MgSiO3 and Mg2Al4Si5O18 causing the changes to the expansion coefficients and thus the rifts between the electrolyte and the connecting members. And the alkaline earth element itself is likely to produce the compound when reacting with the cathode, increasing the battery resistivity of the fuel cell. Despite the addition of B2O3 could reduce the viscosity and increase the wet-ability, B2O3 could be subject to volatility because of its low melting point and could produce HBO2 and B(OH)3 in reduction environment.
However, most of the published research papers continue their use the alkaline earth elements or boron as the glass modifier, which may not be suitable in the glass packaging material in the SOFC applications that are used in the high temperature environment for the extended period of time.
In addition, the conventional glass packaging material when used in the solid oxide fuel cell may be resulting in the inter-diffusion among the connecting members and the components, which in turn could diminish the packaging capability after the extended use. Therefore, while overcoming the above problem, and ensure the applicability of the glass packaging material in the SOFC applications without lead, boron, and alkaline earth elements and excluding the mixture with ceramic powder the present disclosure could still serve the packaging function in the 600-800-degree Celsius temperature range.